In recent years, weight reduction of vehicles has been desired, and thus weight reduction of respective parts constituting vehicles has proceeded. A lamp (lamps) is also included as one of vehicle parts that are required to reduce the weights thereof.
In general, a vehicle lamp has a lamp body having a front opening, a front cover attached to block the front opening, an extension, a reflector, a light source, an electric component, and the like. The reduction of the weight of the lamp body which is generally made of a resin material and has a relatively high proportion of the total weight of the vehicle lamp is considered to be effective in reducing the total weight of the aforementioned vehicle lamp.
A resin molded product formed using a resin material is not sufficient in strength and the like if formed using the resin only. Thus, a filler is generally added to a base resin. Generally, a mineral material having a relatively high specific gravity such as talc is used as a filler suitable for a resin molded product requiring a mechanical strength and the like.
Therefore, in the case of a resin molded product formed using a resin material, in reducing the weight while maintaining the strength thereof, using a material having a lower specific gravity as a filler is considered to be effective.
PTL 1 discloses a technology for obtaining a molded product with a resin composition containing polypropylene and plant fibre.
Generally, a vehicle lamp having a lamp body having a front opening and a front cover attached to block the front opening uses a hotmelt adhesive for bonding between the front cover and the lamp body.